Noor, Ervina Efzan Mhd
(2013)
A Research On The Potential Of Local Natural Fiber To Produce Handmade Papers For Drawing, Painting And Printmaking.
PhD thesis, Universiti Sains Malaysia.
Abstract
The increased use of electronic devices has increased the usage of solder
connections. Lead, the prime solder hitherto used, is hazardous to human health and
the environment. Thus, replacing Sn-37Pb with a lead-free solder is one of the most
important issues in the electronics industry. As such, the characteristics of In-Bi-Sn
and In-Bi-Zn compared with that of the Sn-Ag-Cu solder alloy were studied. In the
differential scanning calometry analysis, In-Bi-Sn and In-Bi-Zn system alloys
presented a low melting temperature of 61.3 °C and 72.3 °C, respectively. Surface
tension and contact angle of In-Bi-Sn and In-Bi-Zn lead-free solder alloys were
measured on Cu substrate and different surface finishes at 100, 120 and 140 °C
reflow. Sessile drop measurements showed that the contact angle depended on the
reflow temperature. The contact angle gradually decreased from 30.76° to 17.25° as
reflow temperature increased from 100 to 140 °C and for In-Bi-Sn and In-Bi-Zn
solder alloy on Cu substrate, ranged from 58° to 7° after wetting on Ni/Cu substrate
at the same reflow temperature range (100 to 140°C). Energy-dispersive X-ray
analysis found two layers of intermetallic compound in the In-Bi-Sn solder alloy:
Cu6Sn5 and Cu11In9 (scallop shaped) and Cu11In9 (brightly coloured) with Cu and
Sn/Cu substrate. The IMC between the In-Bi-Zn solder alloy could be observed:
Cu5Zn8 (continuous planar) and Cu11In9, a minor IMC layer with Cu and Sn/Cu
substrate. However, only one type of IMC was formed between both solders (In-Bi-
Sn and In-Bi-Zn) and Ni/Cu substrate, which was InNi2. As the reflow temperature
increased, the shear strength of the In-Bi-Sn and In-Bi-Zn solder alloys on Cu, Ni/Cu
and Sn/Cu joints improved due to reduced contact angle and larger spreading area.
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